1. Field of the Invention
The present invention relates to a coating and developing apparatus performing a coating treatment of a resist solution and a developing treatment after exposure, on a substrate such as a semiconductor wafer, an LCD substrate (a glass substrate for a liquid crystal display) or the like.
2. Description of the Related Art
In a manufacturing process of a semiconductor device and an LCD substrate, a resist pattern is formed on a substrate by a technique called photolithography. This technique is performed by a series of processes by applying a resist solution to a substrate such as a semiconductor wafer (hereinafter, referred to as a “wafer”) to form a solution film on the front surface of the wafer, exposing the resist film to light using a photomask, and then performing a developing treatment thereon to obtain a desired pattern.
Such treatments are usually performed using a resist pattern forming system in which an aligner is connected to the coating and developing apparatus performing coating and development of the resist solution. In this system, for example, carriers 10 each housing many wafers therein are carried into a carrier stage 11 of a carrier mounting section 1A, and the wafers in the carriers 10 are delivered by a delivery arm 12 to a treatment section 1B as shown in FIG. 16. In the treatment section 1B, formation of an anti-reflection film in an anti-reflection film forming module (not shown) and formation of a resist film in a coating module 13 are performed on the wafers, and the wafers are then carried to an aligner 1D via an interface section 1C. On the other hand, the wafers after exposure processing are returned back to the treatment section 1B and subjected to a developing treatment in a developing module 14, and then returned back to the original carriers 10. Before and after the formation treatments of the anti-reflection film and the resist film and before and after the developing treatment, heating treatments and cooling treatments of the wafers are performed. Heating modules performing the heating treatments, cooling modules performing the cooling treatments and so on are arranged in multi tiers in shelf modules 15a to 15c, and the wafers are carried between the modules by main arms 16A and 16B provided in the treatment section 1B.
When the wafers are subjected to the above-described treatments, the wafers are carried according to a carry schedule (see FIG. 17) in which the timing when each wafer is carried to which module is determined in advance for all of the wafers to be treated as described in Japanese Patent Application Laid-open No. 2004-193597. The vertical axis of the carry schedule shows the cycle and the horizontal axis shows the module to which the wafer is to be carried. Note that FOUP is the carrier and M1 to M6 are the modules, and L1-1 means the first wafer in a lot L1, and L2-3 means the third wafer in a lot L2. In this case, one carrier is allocated to one lot, and three wafers are housed in one carrier in this example.
As described above, the carrier 10 is usually prepared for each lot for treatment, and the wafers taken out of one carrier to the treatment section 1B are subjected to predetermined treatment and processing in the treatment section 1B and the aligner 1D, and then housed in the original carrier 10. In this event, a plurality of, for example, four carriers 10 are mounted on the carrier stage 11 and, for example, the delivery arm 12 is configured to be accessible to all of the carriers 10. The vacant carrier 10 after the wafers therein have been taken out to the treatment section 1B is waiting on the carrier stage 11 until predetermined treatments and processing for the wafers are completed. Then, after the treated wafers W are returned into the four carriers 10, the carriers housing the treated wafers are exchanged with carriers housing untreated wafers. On the other hand, the throughput of the treatment section 1B and the aligner 1D is about 130 wafers per hour. The treatment section 1B and the aligner 1D are configured to be able to perform treatments and processing on, for example, 130 wafers at the same time,
Incidentally, manufacturing of a wide variety of products in small quantities by one coating and developing apparatus is required in recent years. In this case, one carrier is allocated to one kind of products, and therefore the number of wafers housed in one carrier is decreased. Accordingly, in the method of performing all of the treatments on the wafers W in the four carriers 10, returning the treated wafers W back to the original carriers 10, and then exchanging the carriers with new carriers as has been described, the total number of wafers W taken out of all of the carriers 10 mounted on the carrier stage 11 to the treatment section 1B is decreased. Therefore, in the treatment section 1B and the aligner 1D, the wafers are not supplied to all of the modules which could normally perform treatments, resulting in a reduction in throughput.
Therefore, the present inventors have studied provision of a stocker temporarily storing the carriers separately from the carrier stage so that even when the number of wafers housed in one carrier is small, the total number of wafers to be taken out of all of the carriers mounted on the carrier stage to the treatment section is increased by taking the wafers out of one carrier, then retreating the carrier to the stocker, and mounting a new carrier on the carrier stage and taking the wafers out of it, so as to increase the operating rate of the modules in the treatment section and the aligner, thereby suppressing the reduction in throughput.
Incidentally, in the above-described coating and developing apparatus, when the wafers cannot be carried according to the above-described carry schedule due to a failure or the like of the modules or the carry mechanism, an alarm is outputted to shut down the apparatus after the wafers are collected. In this event, the wafers W in the treatment section and the aligner are immediately collected from the modules in which the wafers W are placed at the trouble to the original carriers.
If the stocker is not provided here as in the prior art, all of the wafers placed in the treatment section and the aligner are housed into the carriers provided on the carrier stage, so that the collection work can be quickly performed. However, in the structure in which the stocker for the carriers is provided, a situation that the original carrier to which the wafers W are to be returned does not exist on the carrier stage when trouble occurs may happen, thus generating confusion in the collection work.